While many researchers look for
thenext big idea, Saw-Wai Hla takes a somewhat more minuscule view of things.

“One of the goals of nanotechnology is to make things smaller and smaller,” said Hla, a physics
and astronomy professor at Ohio University.

Much of the current nanotechnology, from computer chips to portable electronic devices, is
produced using a top-down approach. Bulk materials are broken down until they take on the character
of microscopic materials.

But as technology develops, some researchers say they hope to take a bottom-up approach to
construct, atom by atom, nanomaterials that can perform specialized tasks in fields such as
medical, computer and environmental sciences.

For example, some researchers envision devices that could remove pollution from water or the air
on an atomic level, or molecular tools that could attack diseases in the body or sweep blood clots
from clogged arteries.

Hla, along with an international team of scientists, might have moved closer to controlling this
bottom-up approach by designing a molecular motor, something that these devices would need.

He worked with a number of researchers, including Christian Joachim and Gwenael Rapenne with the
National Center for Scientific Research in France.

Their work, funded in part by the U.S. Department of Energy and described recently in the
journal
Nature Nanotechnology, was the first to create a stand-alone molecular motor that uses
multiple parts.

The motor consists of three components — a tripod fixed to a surface, an attached atom that acts
as a ball bearing and five iron atoms that make up the arms of the motor.

The researchers used sulfur, which acts as an atomic glue, to attach the atoms. The motor is
about 2 nanometers long and 1 nanometer tall.

How small is that? One nanometer is one-billionth of a meter. Think of it this way: if a marble
was 1 nanometer around, then Earth would be about 1 meter around. Or this: A sheet of paper is
about 100,000 nanometers thick.

Researchers demonstrated that they could control the motor with energy generated from the
electrons on a powerful scanning microscope.

“This ... is a molecule machine constructed to understand the laws of physics and to force us to
develop new instruments adapted to their scale,” Joachim said in an email.

Hla said if the team were to build a usable motor, electrodes could be installed on the surface
to create an energy source.

Although this motor is simple, future applications could include more-complex machines with
components that could be automated.

“People might look at similar molecules for drug delivery,” said Jay Gupta, a physics professor
whose Ohio State University lab studies structures at an atomic level.

Hla said he envisions that after materials are created with top-down methodology, molecules
could then be allowed to self-assemble, employing a bottom-up approach that supplements existing
technology.

Hla said he sees practical applications to this technology in nanocomputers and nanoelectronics,
although he said some of the applications might be years away.